Log: Result without query?

Hi all!
The Log (Log-Level is 256) of my openldap 2.0.11 shows me results for
Operations without any Query.
Log:
slapd[2723]: conn=122 op=12 RESULT tag=101 err=34 text=invalid DN
As I understand, conn is the Connection-number and op is the
Operation-number. So here, I have a Connection-number of 122 and an
Operation-number of 12. Since the log says "RESULT", there has to be an
Operation for which this line shows an error as the result. But there is
no other line (as with every other operation) indicating what
Operation-number 12 was supposed to do, the result-line only showing
that it failed.
Where does this error come from?
Why is no other line with the query of op=12 in the log?
Thanks for your help.
Timo Boettcher